This is a multiple-center, double-blind, randomized, placebo-controlled, multiple-dose, parallel-group study to compare the changes in the glomerular filtration rate (GFR) and urinary prostaglandins after administration of SC-58635 or naproxen to patients with stable chronic renal insufficiency. Changes in plasma renin activity (PRA), sodium, potassium and creatinine clearances, serum thromboxane B2 and urinary 11-dehydro TxB2 will also be compared between treatment groups.